1997 F150 4.6 Triton V-8. The truck shudders when idling. The shaking lessens when accelerating. The shaking intensifies when trying to maintain around 40 mph around the city. Someone told me to drive with the Overdrive off, and that helps a lot with the shaking. I was able to drive on the highway with the overdrive on and the shaking didn't happen when trying to maintain that speed. I even used cruise control at that speed. My Hanes book doesn't mention Overdrive in the Index section, so any insight is greatly appreciated. Are these symptoms of a failing overdrive, or tranny, or...?

Thanks!

 

Sounds like failing plugs.

I'd replace your plugs.

I think the '97 4.6 has coil on plug... but not sure off the top of my head. If not, replace either the coils or replace wires and the electronic distributor.

 

Truck needs a tuneup. New Motorcraft plugs and spark plug wires. *Might* be a faulty coil, but do the basic stuff first.

The 4.6 in the F150 didn't get COPs until a few years down the road from '97. I think it was 2000.

 

Thanks. I replaced the plugs an wires. It has 2 coil packs. I replaced each one at different times, and this issue started after I replaced the 2nd coil pack. So yeah, it could be a faulty coil pack. I was questioning that line of reasoning after I tried turning off the Overdrive and the heavy shaking pretty much went away. I'll try replacing the 2nd coil pack again and see if that helps.
Thanks!

 

Hope you torqued the plugs to about 28 ft lbs or they may blow out.

 

Are you sure you got the wires on the right terminals when you replaced the coil packs?

 

<<<---- Yeah, this is most likely the issue.

 

 

the only reason it "goes away" when you lock out O.D. is you have raised the RPMS about 30% so it is less NOTICEABLE....still happening...just not noticed as much.